Family: Oleaceae.
See also: Olive

Olea europaea, the Olive tree, has been recognized as one of the most important causes of seasonal respiratory allergy in the Mediterranean area, and in other parts of the world where this tree is now grown. In these place the prevalence of atopic sensitisation to pollen from this tree can be expected to be very high.

Olive tree probably originated in Asia Minor, spread to the Mediterranean region, and was then introduced into North America (especially California and Arizona), South America (Chile), Australia and South Africa. Although in North America Olive trees are found only in the Southwest, Ash and Privet are widespread, a detail of relevance to cross-reactivity. (Kernerman 1992 ref.170 64) 2 Countries and regions have distinct varieties of Olive. In Italy, varieties of Olea europaea, which differ between the northern and southern parts of the country, can induce different IgE-mediated reactions. (Wheeler 1992 ref.4775 6)

Olive tree belongs to a family consisting of more than 30 genera and 600 species.

The Olive tree is an evergreen growing to 10m, with a broad, round crown and a thick and knotty trunk. The flowers are hermaphrodite (have both male and female organs). The plant is self-fertilising. Pollination is by insects but also by wind when pollen is in abundance. The pollination period of Olea varies. It occurs in the spring, but in Europe may start as early as January, depending on the region. (Liccardi 1996) 1 In southern Italy it lasts from early April to late June, and as one moves north, until July. (Wheeler 1992 ref.4775 6)

Olives grow in plantations and woods, and as scrub in dry rocky places. Olive is famous for its fruits and oil, and its by-products are used in making soap. Olive fruits are popular, especially in the Mediterranean, as a relish and flavouring for foods. The fruit is usually pickled or cured with water, brine, oil, salt or lye. Olives can also be dried in the sun and eaten without curing when they are 'fachouilles'. The seed is rich in an edible, non-drying oil; this is used in salads and cooking and, because of its distinct flavour, serves as a condiment. Olive wood is used in cabinet-making as well as in other woodworking and even jewellery-making.

The olive tree flowers in the spring, and the fruit ripens in the fall and winter.

Carob, willow, poplar, olive and cypress pollens were among important inhalant allergens causing skin test positivity in this Turkish region. (Guneser 1996 ref.3250 4)

In this olive pollen allergic family, a HLA class II DR3-DQ2 association was demonstrated (Kalogeromitros 2001 ref.4097 4)

Allergens/Function:

Allergens:
Ole e 1 , a major allergen, comprising a 18.5 nonglycosilated form and a second varient, a 20 kDa glycosilated polypeptide. Affects more than 70% of patient. It is a glycoprotein. (Obispo 1993 ref.4742 6) (Villalba 1994 ref.4757 4) (Batanero 1999 ref.4762 2) (De Cesare 1993 ref.4770 8) (Carnes 2002 ref.6957 3)
Ole e 2, a 15-18 kDa protein, a profilin, a major allergen (Lauzurica 1988 ref.4758 5) (Rodriguez 2002 ref.6947 3) (Martinez 2002 ref.6956 1)
Ole e 3, a 9.2 kDa, calcium-binding protein (Batanero 1996)
Ole e 4, a major allergen (Boluda 1997 ref.4759 6) (Boluda 1998 ref.4760 6) (Carnes 2002 ref.6957 3)
Ole e 5, superoxide dismutase (Boluda 1997 ref.4759 6) (Boluda 1998 ref.4760 6) (Carnes 2002 ref.6957 3)
Ole e 6, approximately 10 kDa. (Carnes 2002 ref.6957 3)
Ole e 7, a major allergen, approx 10 kDa. (Tejera 1999 ref.4100 7)
Ole e 8, calcium-binding protein, a major allergen (Ledesma 2002) (Rodriguez 2002 ref.6947 3)
Ole e 9, a 46.4 kDa, a major allergen, a 1,3-beta-glucanase protein (Huecas 2001 ref.4664 3) (Rodriguez 2002 ref.6947 3)

Not all allergens are found in every Olive tree cultivar. In a study examining the various IgE-binding proteins of the pollen extracts of the various Olive tree cultivars, 6 predominant IgE-binding bands, some of which appear in all the cultivars, were found. An 18 - 20-kDa band (Ole e 1) appeared in only 8 of the cultivars, but not in the 9 others. (Waisel 1996 ref.4750 9)

Martinez reports on the identification of a new 36-kDa Olive-pollen allergen, which 83% of the sera from O. europaea-allergic patients recognised. 79% of this patient group were positive on intradermal tests. Extracts from Olive pollens collected in California demonstrated a much higher amount of the 36-kDa protein than those from pollens of Spanish origin (approximately 16-fold higher). The presence of similar allergens was detected in the closely related species Syringa, Fraxinus, and Ligustrum. (Martinez 1999 ref.3332 5)

20% were sensitized to olive pollen profilin (Ole e 2). (Martinez 2002 ref.6956 1)

Of the number of allergens isolated and characterised from Olive pollen, Ole e 1 is the most frequent sensitising agent, affecting more than 70% of the patients with sensitisation to Olive pollen, although others, such as Ole e 4 and Ole e 7, have also been shown to be major allergens. The prevalence of many Olive pollen allergens is dependent on geographical location. Some of the Olive allergens have been revealed as members of known protein families: profilin (Ole e 2), Ca(2+)-binding proteins (Ole e 3 and Ole e 8), superoxide dismutase (Ole e 5) and lipid-transfer protein (Ole e 7). No biological function has been demonstrated for Ole e 1, while Ole e 4 and Ole e 6 are new proteins without known homology to other allergens. (Rodriguez 2001 ref.4307 0)

Ole e 9 is found in the sera of 65% of patients suffering olive pollinosis. (Huecas 2001 ref.4664 3)

In this study examining the various IgE-binding proteins of the pollen extracts of the various Olive tree cultivars, 6 predominant IgE-binding bands, some of which appear in all the cultivars were found. An 18-20-kDa band (Ole e 1) appeared in only eight of the cultivars, but not in the nine others. (Waisel 1996 ref.4750 5)

Pollen from 6 different O. europaea varieties collected in southern Spain were studied demonstrated great differences in the in vivo and in vitro potency of the extracts. There were significant differences in the Ole e 1 content, while the protein content remained very similar in these extracts. This study confirms previous observations of a great variability in the antigenic and allergenic composition of O. europaea pollen extracts and establishes significant differences in Ole e 1 content. (Carnes 2002)

Olive tree pollen contains at least 3 calcium-binding sites all being able to induce IgE-mediated allergy. (Ledesma 2002 ref.6029 3)

The most prevalent olive allergen is Ole e 1, which affects more than 70% of patients hypersensitive to olive pollen, but others, such as Ole e 2, Ole e 8, and Ole e 9, have been demonstrated to be major allergens, and Ole e 6 or Ole e 7 reach high values of clinical incidence. Many of these allergens, such as Ole e 2 (profilin) and Ole e 3 (polcalcin), are involved in cross-reactivities, which agrees with their adscription to panallergenic families. Ole e 1 also exhibits IgE-binding determinants in the carbohydrate, which are recognized by more than 60% of the sera from patients sensitive to the whole allergen, although the level of such glycan-specific IgE seems not to be clinically relevant in the overall content of the sera. (Rodriguez 2002 ref.6947 3)

One-hundred and seven (90.7%) patients had a positive skin response to Ole e 1; 88 (74.6%) reacted to Ole e 2; 57 (47.9%) reacted to both Ole e 6 and Ole e 7; and 43 (37.8%) reacted to Ole e 3. The allergenic activity determined by ELISA to Ole e 1 was found in 84%; to Ole e 2 in 61.3%; to Ole e 3 in 31.9%; to Ole e 6 in 39.4%; and to Ole e 7 in 41.2% of patients. All patients had positive skin responses to at least one of the allergens tested, However, a combination of Ole e 1 and Ole e 2 together with a minor allergen Ole e 6 or Ole e 7, disclosed the same diagnostic value that was obtained with the use of crude olive pollen extract. (Quiralte 2002 ref.6948 2)

Adverse Reactions:

IGE AND IMMUNE:
Pollen from this tree results in asthma, allergic rhinitis and allergic conjunctivitis in sensitised individuals. (Pajaron 1997 ref.2353 6) (Soriano 1999 ref.4755 5) (Cortes 1998 ref.4763 4) (Ramadan 1998 ref.4764 2) (Prados 1993ref.4768 0) (De Benedetto 1989 ref.4776 4) (Liccardi 1997 ref.4781 4) (Liccardi 1996)

Asthma, allergic rhinitis and allergic conjunctivitis. In Europe, olive-sensitization is frequently found in pollen-positive subjects with allergic rhinitis. (De Benedetto 1989 ref.4776 4)

Olea europaea, the olive tree, has been recognized as one of the most important causes of seasonal respiratory allergy in the Mediterranean area. Olive pollinosis is quite rare in the form of monosensitization, and in these patients, symptoms are perennial rather than seasonal. (Liccardi 1996) (Blanco 1992 ref.4748 4) (Carreira 1995 ref.4749 3)

Cross-reactivity between olive and Ash has been observed. At least 10 allergenic components have been identified from olive pollen.

Systemic reactions occurring during immunotherapy. (Hejjaoui 1992 ref.4825 4)

The frequency of sensitisation to Olive tree pollen varies in the Mediterranean region from 12% in Sicily to 37% in Greece.(Liccardi 1996)(D'Amato 1994 ref.4744 3) In Greece, more than 37% of atopic individuals are sensitised to Oleaceae. (Gioulekas 1991) Fifteen percent of atopic patients in southern France were found to be skin-prick positive to Oleaceae. (Bousquet 1984 ref.4396 3) In Italy, atopic sensitisation varied between 12.2% in Sicily to 30% in Apulia.(Caiaffa 1991)(Purello D’Ambrosio) (Fanti 1989) (Corsico 2000 ref.4101 2) (Ariano 1999 ref.4753 4)

In Naples, of 4,142 patients examined consecutively over a two-year period, 13.49% of adults and 8.53% of children of all skin-prick test positive patients tested positive to Olea pollen allergens on skin prick testing. (Liccardi 1994) Less than 1.4% of children and 2.3% of adults were found to be monosensitised to Olive pollen. (Liccardi 1994) In this study on 507 asthmatic atopic children in the Chieti-Pescara area of Italy, skin-prick tests found that 21% were sensitized to Olive tree pollen. (Verini 2001 ref.4665 3)

Sensitisation to Olive pollen has been reported in Israel. (Tamir 1991 ref.4746 3) (Rachmiel 1996) Positive skin reactions to Olive pollen, among atopic patients of the Jewish population, was shown to be high where Olive trees are abundant (66%), and lower (29%) where the trees are scarce. (Geller-Bernstein 1996 ref.4766 6) (Geller-Bernstein 1994 ref.4767 2) In Spain, a study demonstrated that the frequency of sensitisation could vary greatly within the same country. (Silva Palacios 1997 ) (Caballero 1996) The daily pollen concentration in the atmosphere showed pollen from the Olive tree to be one of the most frequent pollen grains detected. (Silva Palacios 2000 ref.4732 3)

Olive tree pollen has also been shown to result in sensitisation in Japan, where 16.3% of pollinosis patients were positive to this allergen. (Miyahara 1995 ref.4739 0) (Geller-Bernstein 1994 ref.4767 9) Skin-prick tests for sensitisation to Olive tree pollen in the southern part of Switzerland (Canton Ticino) showed a high sensitisation rate of 54%. (Gilardi 1994 ref.4549 8)

The majority of studies demonstrate a higher prevalence of rhinoconjunctival symptoms than asthma. (Liccardi 1996) Patients are more likely to be polysensitised than monosensitised to Olive tree pollen. Monosensitised individuals, children and adults, have symptoms throughout the year without an apparent increase during the Olive pollination season. (Liccardi 1996) (Blanco 1992 ref.4748 4)

In this study from Malaga, southern Spain, 20.4% of 365 students, of which 19.9% suffered from rhinoconjunctivitis, 4.1% rhinoconjunctivitis plus asthma, 3.1% asthma alone, and 0.8% atopic dermatitis, were atopic to Olea. (Garcia-Gonzalez 1998 ref.4943 2)

NON IMMUNE:
Unknown or Nil